Use a sub or difference identity to find exact value of the

Solution

given tan(15^o) = tan(45-30)

tan (A -B) = (tan A - tan B)/(1 + tan A tan B)

= (tan 45 - tan 30)/(1 + tan 45 tan 30)

= (1-1/sqrt3) /(1+1/sqrt3)

=(sqrt3 -1)/(sqrt3 +1)

= 0.26795